SciPost Submission Page
Sum frequency generation from real-time simulations in two-dimensional crystals
by Mike N. Pionteck, Myrta Grüning, Simone Sanna, Claudio Attaccalite
Submission summary
| Authors (as registered SciPost users): | Claudio Attaccalite |
| Submission information | |
|---|---|
| Preprint Link: | scipost_202505_00003v1 (pdf) |
| Date submitted: | May 2, 2025, 12:05 p.m. |
| Submitted by: | Attaccalite, Claudio |
| Submitted to: | SciPost Physics |
| Ontological classification | |
|---|---|
| Academic field: | Physics |
| Specialties: |
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| Approaches: | Theoretical, Computational |
Abstract
Sum frequency generation (SFG) and difference frequency generation (DFG) are second order nonlinear processes where two lasers with frequencies $\omega_1$ and $\omega_2$ combine to produce a response at frequency $\omega = \omega_1 \pm \omega_2$ . Compared with other nonlinear responses such as second-harmonic generation, SFG and DFG allow for tunability over a larger range. Moreover, the optical response can be enhanced by selecting the two laser frequencies in order to match specific electron-hole transitions. Here, we propose a first-principles framework based on the real-time solution of an effective Schr\"odinger equation to calculate the SFG and DFG in various systems, such as bulk materials, 2D materials, and molecules. Within this framework, one can select from various levels of theory for the effective one-particle Hamiltonian to account for local-field effects and electron-hole interactions. To assess the approach, we calculate the SFG and DFG of two-dimensional crystals, h-BN and MoS$_2$ monolayers, both within the independent-particle picture and including many-body effects. Additionally, we demonstrate that our approach can also extract higher-order response functions, such as field-induced second-harmonic generation. We provide an example using bilayer h-BN.
Author indications on fulfilling journal expectations
- Provide a novel and synergetic link between different research areas.
- Open a new pathway in an existing or a new research direction, with clear potential for multi-pronged follow-up work
- Detail a groundbreaking theoretical/experimental/computational discovery
- Present a breakthrough on a previously-identified and long-standing research stumbling block
Author comments upon resubmission
Thank you for sending us the referee's report, which we found very positive.
As suggested, we have responded directly to the referee's comments/observations,
and have resubmitted a revised version of our manuscript, which we now consider more suitable for publication in SciPost.
Below is the list of changes made to the manuscript, also highlighted in red in the text.
Kind regards.
Claudio Attaccalite
List of changes
Here the list of changes in the new version of our manuscript:
1) We updated Ref.31 and Ref. 34 that are now published
2) We added a note to explain that TD-aGW was called TD-HSEX/TD-SEX in previous papers
3) Fixed all abbreviations in references
4) fixed typos
5) We condensed the discussion about problematically long periods at the beginning of Sec. 3.2
6) We changed the introduction of the paragraph about two similar frequencies in Sec. 3.2.1
7) We changed Fig. 3. In the full DFT approach, we used 435 fs sampling time after 40 fs dephasing. For a fair comparison with the other approaches where a 50 fs dephasing is applied, we start also with a 50 fs dephasing in the full DFT approach. Then a simulation time of 385 fs is considered converged. Furthermore, the difference for SVD and LSF in logarithmic scale with 5 fs less sampling time is add to show convergence.
8) We explained why SVD and LSF provide same results and that they are equally efficient according to our tests.